Method of incorporating carbon black and other materials into elastomers



April 30, 1968 L. H. REES 3,380,

METHOD OF INCORPORATING CARBON BLACK AND OTHER MATERIALS INTO ELASTOMERSFiled Dec. 25. 1966 4 Sheets-Sheet 1 April 30, 1968 H. REES 3,380,958

METHOD OF INCURYORATING CARBON BLACK AND OTHER MATERIALS INTOEILASTOMERS Filed Dec. 25. 1966 4 Sheets-Sheet Ina 24222502 Lg/72 7/4flifiu ney Aprll 30, 1968 1.. H. REES 3,380,953

METHOD OF INCOBPORATING CARBON HLACK AND OTHER MATERIALS INTO ELASTOMBRSFiled Dec. 23, 1966 4 Sheets-Sheet a ll Aprll 30, 1968 L. H. REES3,380,958

METHOD OF INCORPORATING CARBON BLACK AND OTHER MATERIALS INTO ELASTOMERSFiled Dec. 23, 1966 4 Sheets-Sheet 4 O O O United States Patent3,380,958 METHOD OF INCORPORATING CARBON BLACK AND OTHER MATERIALS INTOELASTOMERS Lancelot H. Rees, Westwood, Mass., assignor t0 Mauton GaulinManufacturing Company, Inc., Everett, Mass, a corporation ofMassachusetts Continuation-impart of application Ser. No. 248,461, Dec.31, 1962. This application Dec. 23, 1966, Ser. No. 611,520

Claims. (Cl. 26041.5)

ABSTRACT OF THE DISCLOSURE The method of the invention involves thepreparation of a premix in which two different classes of solids, i.e.carbon black particles and a rubber polymer in suitably proportionedquantities are dispersed in a highly uniform state of dispersion in acommon liquid phase. The resulting system while in a highly uniformstate of dispersion is conducted into a high pressure pumping apparatuswhich instantaneously subjects the mass to controlled pressures in arange of from 500 to 8000 psi. and which releases the pressure throughan orifice with the generation of intense cavitational field forces tocause the carbon black to pass into a very fine state of subdivision andto induce transition of the subdivided carbon particles from their waterphase to the polymer phase in chemically bonded relationship.

This application is a continuation-impart of application Ser. No.248,461 filed Dec. 31, 1962, now abandoned.

The present invention, as well as the earlier application referred torelates to methods of reinforcing rubber and, more particularly, theinvention is concerned with improved procedures for incorporating carbonblacks in rubber latices of either natural or synthetic type whereby therubber polymer is preserved and the carbon blacks may be combined withthe rubber polymer to provide significantly more efl'ective rubberreinforcement.

Carbon blacks as generally referred to may include a group of submicronsize pigments consisting of essentially pure carbon and producedcommercially in such forms as channel black, furnace black, acetyleneblack, thermal black and others. These commercial carbon blacks occur inparticle sizes ranging from about to 500 milli-microns and it is wellknown that in using carbon blacks as a reinforcing agent in natural andsynthetic rubber the most important variable affecting reinforcement isparticle size with reinforcing properties increasing as particle sizedecreases.

It is also well known to those skilled in the art that carbon particleshave a strong tendency to form aggregates and this tendency increases assubdivision is extended. The carbon aggregates are held together withvarying degrees of bond strength depending upon the fuel from which theyoriginate and the type of production process employed. It is also knownthat excessive mechanical working may result in excessive polymerdegradation to a point where rubber reinforcement decreases undesirably.

Because of these limiting factors in both the carbon and rubber polymerdifficulty is present in maximizing rubber reinforcement especially whenattempting to combine carbon particles in an aqueous dispersion withsolids in an aqueous latex dispersion.

In conventional mixing of carbon black with rubber to providemasterbatches having superior strength and abrasion resistance such asis required for tire treads or insulation purposes, best results areobtained by using carbon black in a dry state worked with a Banburymixer. Less satisfactory results are obtained when an aqueous carbonblack dispersion and latex are mixed although the rubber is used forthese purposes and lower costs are realized.

Various procedures for using aqueous carbon black dispersions have beenproposed in the art as disclosed, for example, in Sutherland Patent3,055,856-Hull Patent 3,085,988 and Braendle Patent 2,769,795 andothers. However, up until the present time aqueous carbon blackdispersons have not been successfully used so far as I am aware toprovide a product of tensile strength and abrasion resistance equal tothat obtainable with dry masterbatching using a Banbury mixer or arubber roll machine.

It is a chief object of the present invention, therefore, to improvemethods of incorporating aqueous carbon black dispersions with laticesand other elastomers and to devise a technique for producingmasterbatches with latex and aqueous carbon black dispersions whosestrength and abrasion resistance are of substantially improved charactercomparable with the strength and abrasion resistance obtained by drymasterbatching.

Another object of the invention is to devise a method of mixing anaqueous carbon black dispersion with latex in a more intimatelyincorporated relationship to obtain a chemical bonding between extremelyfinely divided solids of latices and carbon particles in asignificantdegree not heretofore accomplished in the art.

Another important objective is to provide a method of pressurizingcarbon particles and elastomer constituents in which a state ofsubdivision is realized at which a unique absorption of carbon by theelastomer is caused to take place.

A further object of the invention is to provide an improved method ofintroducing coagulating and creaming agents to carbon black and latexmixtures. Still another object is to provide improved methods ofcontrolling the degree and character of coagulation operations inproducing a rubber crumb either with or without extenders, accelerators,fillers, vulcanizers and the like.

The nature of the invention and its other objects and novel featureswill be more fully understood and appreciated from the followingdescription of preferred embodiments selected for purposes ofillustration and shown in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view illustrating one desirable form of themethod of the invention;

FIGURE 2 is a diagrammatic view illustrating another form of theinvention and particularly indicating the use of a brine for coagulatingpurposes;

FIGURES 3 and 4 are diagrammatic views further illustrating othermodified forms of the invention;

FIGURE 5 is a diagrammatic view showing a curve of tensile strengthvalues plotted against cure time to illustrate improved properties ofrubber products from masterbatching in accordance with the invention;and

FIGURE 6 is another diagrammatic view illustrating a curve of tensilestrength values plotted against elongation of samples produced by drymasterbatching in comparison with aqueous carbon black masterbatching inaccordance with the invention.

From a consideration of the foregoing objectives and an examination andstudy of the conditions out of which they arise, I have conceived of anovel carbon dispersion technique based on the idea of instantaneouslyseparating carbon black particles into an extremely finely divided stateand simultaneously incorporating the carbon particles, while passingthrough this change of state, with a latex dispersion at a point atwhich the latex is also caused to undergo rapid transitional changes atexceedingly high energy levels whereby chemical bonding is induced.

I have discovered that this concept may be embodied in one practicalform by subjecting a pre-mixed aqueous carbon black and latex liquid toextremely high levels of energy obtained by pressurizing the mixture atvery high pressure intensities and then instantaneously releasingpressure through a controlled orifice.

I find that by carrying out this pressurizing operation at asufiiciently high range of pressures and by generating an intensecavitational field at the orifice, a point is reached at which the latexundergoes momentary changes in form or composition and simultaneouslythe carbon particles are subdivided to a pronounced extent. As thisoccurs the exceedingly fine particles of carbon become uniformlydistributed throughout all portions of the latex and chemical bondingtakes place with carbon particles being combined with the latex in amanner not heretofore realized in the art of masterbatching. Thesechanges are evidenced in the resultant rubber product by change inphysical properties such as solubility, tensile strength, abrasionresistance and ability to resist release or transfer of carbon whenbrought into contact with other surfaces.

In subjecting the carbon black and latex mixture to suitably high energylevels and generating intense cavitational forces in accordance with theinvention method, I find that pressures of from in the neighborhood of Sp.s.i. up to 8000 p.s.i. may be employed. At these pressures the latexand carbon particles move at very high velocities and the total timerequired to disperse the carbon black and incorporate it into the latexat the resulting energy levels indicated may be as little as one 100thousandths of a second.

I have further found that chemical bonding of carbon particles to latexparticles may be caused to take place in varying degrees and in acontrolled manner. This may, I find, be accomplished by controlling thepressures employed in accordance with several important variables in themix including (a) the type of latex particles dealt with (b) the sizeand composition of the carbon particles being combined and (c) theproportionate amounts of carbon particles and latex solids which areprocessed. Specifically pressure may be controlled or regulated inaccordance with variation in molecular weight of the polymer use in amix, or in accordance with variation in mean surface area per unitweight of carbon used or in accordance with changes in proportions ofcarbon and polymer combined.

1 have further discovered that by employing controlled high energy levelprocessing of the aqueous carbon black and latex, and by regulating thecomposition and pH of the carbon black, I may obtain importantadvantages and I may carry out improved coagulation of the resultantIIllX.

For example, in a system where it is desirable not to have coagulumduring the dispersion step, I may desire to use a pH range of between7-10 for the carbon black. However, in instances where the particularstability of the latex or other polymer permits, or Where I may desireto obtain a degree of coagulum during the dispersion step, I may operatein a pH range of from 3 to 7.

I further find that coagulation may be accelerated by placing a secondrestricted orifice in series with the first orifice and introducing athigh pressure a creaming or coagulating agent such as brine at thesecond orifice. In this way I may continuously and instantaneously creamand coagulate the latex carbon black mixture in a highly advantageousmanner. Regulating pressure at the second orifice may also, I find, notonly accelerate coagulation, but may further operate to control the sizeand extent of coagulation of the latex crumb formed.

Considering these steps in greater detail, FIGURE 1 illustratesdiagrammatically one desirable form of the method of the invention. Asnoted therein, a suitable carbon black such as, for example, a furnaceblack whose pH is controlled as noted above is mixed with water in areceptacle 2, delivered to a tank 4, and circulated through a colloidmill 6. Measured quantities of the aqueous carbon black are conductedthrough a metering device 8 and then into a mixing tank 10. Into tank 10another measured quantity of latex is furnished from a supply container12 through a second meter 14. The mixture of aqueous carbon black andlatex is subjected to agitation, for example, as by means of a mixingdevice as shown at 16' of FIG. 2.

In accordance with the invention method, the fluid mixture thus preparedis drawn into a high pressure pumping mechanism 18 and instantaneouslysubjected to very high pressures in a confined space. Thereafterpressurized fluid material is forced through a restricted orifice 19 inthe presence of intense cavitational forces which are developed byexerting controlled prcssures in the range of. from 500 psi. to 8000p.s.i. Material from the orifice 19 passes into a coagulating andwashing tank 20.

As illustrative of a specific processing operation using definitequantities of carbon black and rubber polymer the following example iscited.

EXAMPLE A Step l.--A slurry of particles of furnace black and water wasprepared by mixing together 9.1 pounds of water occurring in atemperature range of from 60 F. to F. and 9 pounds of a furnace blacksold under the tradename Vulcan 3 and commercially produced by the CabotCompany of Boston, Mass. Vulcan 3 is conventionally used in drymasterbatching and is a furnace black type specified to have an averageparticle diameter of approximately 29 millimicrons.

Step 2.--The resulting slurry was thoroughly mixed by a standardpropeller agitator device capable of producing a uniform distribution ofthe carbon particles in water.

Step 3.This mixture was then passed through a colloid mill of the typeknown as a Manton Gaulin Model 2F Two-Stage Colloid Mill, with a gapsetting between the rotor and stator being set at .010 inch. This model2F colloid mill is manufactured and sold by the Manton GaulinManufacturing Company of Everett, Mass. A period of time ofapproximately 4.5 minutes was required to process the mixture specified.

Step 4.The premixed carbon black slurry was then discharged from thecolloid mill directly into a mixing tank to which was simultaneouslyadded a quantity of latex consisting of 10 pounds of Copolymer 1500manufactured by Polymer Corporation of Baton Rouge, La. The Copolymer1500 consisted of an aqueous dispersion of synthetic latex particleshaving a water-like consistency and containing approximately 18 percentsolids. The aqueous dispersion of latex particles contained a smallquantity of a dispersing agent in the form of a soap material such as astearate which functioned to prevent agglomeration of carbon particlesand provide a stable dispersion.

Step 5.The dispersion of carbon black and latex thus stabilized was thenconducted into a high pressure pumping apparatus and pressurized in acontrolled high energy pressure range by subjecting the mass to apressure of approximately 6000 p.s.i. and instantaneously exposingconstituent particles of carbon and polymer to intense cavitationalforces as the mass is discharged through an orifice.

Step 6.The discharged product was then led into a 1.0 percent solutionof sulphuric acid to produce a coagulated crumb. The resulting crumb waswashed and dried in accordance with standard masterbatching proceduresto produce a final masterbatch crumb product.

The masterbatch crumb prepared in the manner described above whencompared with conventional masterbatch crumb showed distinctive newproperties. It is known that a rubber polymer may be mechanically workedto a point of excessive polymer degradation at which point reinforcementby carbon black begins to decrease rather than increasing further. Inthe invention crumb product it was found that there had been induced inthe latex solids a change in form which approached but did not exceed apoint of excessive polymer degradation. This was evidenced by increasein tensile strength in rubber samples made from the crumb as hereinafterdisclosed.

It was also found that carbon black particles were caused to pass into astate of further subdivision and instantaneously exposed to intensecavitational forces which operate to induce a transition of the carbonparticles from their water phase to the latex solid phase with chemicalbonding taking place in a significant degree. Chemical bonding wasclearly evidenced by (a) change in solubility characteristics of thecarbon and polymer, (b) by change in appearance of the product, (c) bychange in the manner in which the carbon was retained in the polymer and(d) by the change in tensile strength above referred to.

In support of these observations there are noted below several testsconducted with samples of invention crumb made in accordance with theprocedure of Example A and also with similar samples made in aconventional manner.

Test for change in appearance A sample of the crumb product made inaccordance with the procedure of Example A was placed on a lightedviewing surface side by side with a sample of crumb made by mixingcarbon and polymer without high energy level pressurization and the twosamples were carefully compared. A striking change in appearance waspresent in the invention sample as compared with the conventionalsample. The invention sample exhibited a glossy surface whereas theconventional sample exhibited no glossy appearance at any point andoccurred throughout with a dull black surface. The two samples whilestill supported on the lighted surface were thereafter torn apart andseparated into small component pieces and again examined. Here also itwas found that the invention sample retained a glossy appearancethroughout the body portion whereas the conventional sample showedmerely a dull black surface. It was concluded that these twoexaminations clearly indicated a chemically bonded association of carbonin the case of the invention crumb and lack of such bonding in theconventional crumb.

Test for change in carbon marking A sample of the invention crumb wasformed into a small mass and drawn across a sheet of white paper.Similarly, a sample of a conventional crumb in a small mass was drawnacross the same sheet of paper. In the latter case a distinct line ofcarbon black was observed whereas with the invention crumb no lineappeared at all. This indicated again that the carbon in the inventionsample was retained in an entirely different manner necessitating bondedrelationship of carbon to polymer while in the conventional samplecarbon was not held in this manner.

Test for change in tensile strength A sample of the invention crumbproduced by the method described in Example A was provided. The sampleweighed 1.5 pounds. This sample included 1 pound of rubber polymer, .5pound of carbon black and .013 pound of antioxidant and a suitablevulcanizing agent. This sample of product was thereafter subjected tostandard curing procedures using curing periods of 25, 50 and 100minutes.

From the cured rubber sample there was then formed a number of strips ofrubber which were tested with standard tensile strength measuring meansto produce a series of tensile strength determinations which wereplotted to form the tensile strength curve shown in FIG- URE 5.

At the same time a conventional rubber sample was prepared utilizing aconventional masterbatch having the same quantities and materials notedabove but mixed without the high energy processing steps of theinvention. and cured, coagulated, and washed in the manner noted above.From this sample standard tensile strength strips were formed andsubjected to the same tensile strength means to provide another set ofvalues which were plotted to form the curve shown in FIGURE 5 at theright hand side of this figure.

As will be observed from an inspection of the two curves in FIGURE 5, asignificant increase in tensile strength was obtained with the samplesof the invention as compared with samples made from conventionalprocedures for incorporating carbon black in a latex polymer. It willalso be observed from a comparison of the two curves in FIGURE 5 thatthe invention samples reached their peak tensile strength value in amuch shorter cure time as compared with the conventional samples.

Test for change in solubility Four rubber samples were subjected totests by determining solubility in the solvent toluene. Sample No. 1contained no carbon and was subjected to high pressure (8000 p.s.i.).Sample No. 2 contained carbon without high energy level pressureprocessing. Sample No. 3 contained carbon and was subjected to highlevel energy processing at 500 p.s.i. Sample No. 4 was preparedsimilarly to sample No. 3 but was processed at presures of 8000 .s.1. pSAMPLE 1 In preparing Sample No. 1, one-half gallon of copolymer 1500latex from Polymer Rubber Company of Baton Rouge, La. was passed througha high energy level pumping apparatus and subjected to pressures of 8000p.s.i. and then discharged through an orifice into a one percentsulphuric acid solution with agitation. This produced a rubber crumbwhich was given two one-half hour washes in fresh water.

Thereafter, three grams of crumb sample were cut into extremely fineparticles and allowed to swell in ten millilitres of toluene. Afterswelling was complete the volume was made up to 100 millilitres andallowed to stand overnight. The mixture was centrifuged for one hour andthen 50 millilitres of supernatant liquid was poured with stirring into100 millilitres of warm SD30 alcohol. The clot formed was removed andredissolved in toluene, reprecipitated in alcohol, removed, pressed toeliminate solvent and dried to constant weight at C. The resultingdetermination showed a percentage extraction of 0.0.

SAMPLE 2 SAMPLE 3 Sample No. 3 was made with the same materials andamounts specified in Sample No. 2 and the resulting masterbatch ofcarbon black and latex was then subjected to high energy levelpressurizing at 500 p.s.i. before being coagulated with sulphuric acid.This sample when washed and tested for solubility in the mannerdescribed with reference to Samples No. 1 and No. 2 showed a percentageextraction of 56.0.

SA )1 PLE 4 Sample No. 4 was made in exactly the same manner as SampleNo. 3 using the same materials and quantities by sub ecting themasterbatch of carbon black and latex to high energy level processingpressures of 8000 p.s.i. The

resulting product was then coagulated, washed and subjected to the samesolubility test in toluene and showed a percentage extract of 65.3.

From the above extraction percentages it was apparent that a change insolubility of substantial nature had taken place which could only beaccomplished by chemical bonding occurring in a significant degree.Since Sample No. 1 indicated no material extracted, it was to beconcluded that the pressurizing copolymer 1500 was completely insolublewith no carbon present even at a pressure range of 8000 p.s.i. In SampleNo. 2 some combination was present from mixing the carbon black andcopolymer with agitation to a degree equal or greater than that known inthe prior art.

In Samples No. 3 and No. 4 however, sharply increased solubilities wereapparent and equally significant was the fact that the higher pressurelevel produced much greater solubility, i.e. 65.3% compared to 56.0%.These increased solubilities observed are consistent with rubberreinforcement comparable with or equal to that obtained with drymasterbatching.

Additional tests were also carried out corresponding generally toExample A wherein other polymers of varying molecular weights and carbonblack having varying mean surface areas were premixed. In these testsvarying pressures were employed and regulated in accordance with thevariables noted within limits which avoided polymer degradation and yetprovided rubber reinforcement in significantly increased degreecomparable with that obtained by conventional dry masterbatching. Onesuch test is noted below as Example B.

EXAMPLE B Tensile strength curves were plotted as indicateddiagrammatically in FIGURE 6, including a curve at the left hand side ofFIGURE 6 indicating tensile strength resulting from masterbatching inaccordance with the invention, and at the right hand side of FIGURE 6 atensile strength curve obtained with conventional masterbatching asproduced by a Banbury mixer or the like.

In plotting these curves a plurality of tensile strength testing stripswere formed from rubber produced according to Example A, utilizing thesame materials and quantities. At the same time testing strips ofBanbury mixed rubber was provided for comparison purposes. These severaltest samples were then subjected to standard tensile strength testingmeans to provide a series of values which were plotted to form the twocurves in FIGURE 6. It will be observed from an inspection of these twocurves of FIGURE 6 that the bonded relationship of the carbon at thehigh energy pressure levels specified has resulted in a rubberreinforcement of a degree comparing almost exactly with that obtainedfrom dry masterbatching using a Banbury mixer. Therefore, it may beconcluded that a significant increasein the degree of bonding over anypreviously obtained bonding results has been made possible by the methodof the invention and without loss of rubber reinforcement from excessivepolymer degradation.

In addition to the above-mentioned advantages, it has also been observedthat by proper selection of pressures and pH values of the carbon black,it is possible to coagulate fractionally the latex carbon black mixtureas it is passed through the orifice. These coagulum fractions varywidely in physical properties. For example, the coagulum of one fractionmay be hard and tough, whereas the coagulum of the other fraction issoft and elastic.

It will be observed that in the method illustrated in FIGURE 1, thepressurized material is illustrated as passing into the coagulating tank20 where actual coagulation may be caused to take place. However, anovel feature of the invention method consists in the fact thatcoagulation may actually be induced by utilizing the high pressuresabove-noted and then discharging the processed material into a suitablecontainer.

In FIGURE 2, I have illustrated diagrammatically a modified form of theinvention. The parts noted therein have similar but primed numerals,corresponding to those of FIGURE 1. In this modification I haveillustrated a method of expediting the coagulation process by forming acream of the pressurized material. This is accomplished by supplyingbrine from a brine tank 22. Latex and carbon black are mixed andpressurized in the manner already described. The resulting brine andpressurized fluid from the member 18' is then thoroughly mixed togetherand repeatedly creamed in a creaming tank 24, utilizing a mixer 26'.From the creaming tank 24' the product is transferred into a coagulatingtank 28' for coagulating and washing the coagulated rubber crumb.

In FIGURE 3, I have shown another form of the .invention in which themethod of coagulating may be still further expedited in a desirablemanner. I employ in this modified form of the invention apparatussimilar to that described above including parts 2", 4", 6", 8", 10'',12?, 14", 16", 18", and 22", also a second stage pressurizing device 30which is adapted to exert pressures in a range of from 50 p.s.i. up to1000 p.s.i. This device is located in series with the pressurizingdevice 18". Brine from a brine tank 22 is then introduced between thepressurizing devices 18" and 30, as shown. I have found that this mannerof processing latex carbon black product may result in almostinstantaneous coagulation and that a control of the type and size ofrubber crumb formed can be realized by regulating the pressures utilizedat the second stage. The crumb is then processed in the usual way in acoagulating tank 34.

In FIGURE 4, I have illustrated another modified form of the inventionin which apparatus as above described is employed including parts 42,44, 46, 48, 50, 52, 54, 58 and 60 which are associated together, andbetween the members 50 and 58 I introduce a heating unit 40 by means ofwhich temperature control may be realized.

From the foregoing disclosure it will be apparent that I have discloseda method of processing carbon black and latex in which high energy levelpressurizing is employed and controlled within limits which will avoiddegradation of the particular latex polymer processed and which willfurthermore achieve a degree of chemical bonding of significant extent.It is pointed out that desirable results may be obtained at varyingselected pressure levels within varying controlled pressure levelswithin the range specified depending upon the degree of chemical bondingsought and the materials dealt with. With regard to variation in thecomponents of the mix, it will further be seen that the pressure may becontrolled or regulated in accordance with a number of variables such aschange in the type or particle size of the carbon as well as thevariation in the forms of latex or other elastomer processed, variationin curing technique and other considerations.

I may also desire to carry out the method of the invention in othermodified forms as, for example, by employing other finely dividedreinforcing agents and/or pigments either in place of carbon black, orin conjunction with it, including materials such as extender oils,accelerators, fillers, vulcanizers and the like.

Various other changes and modifications may also be practiced in keepingwith the scope of the invention as defined by the appended claims.

I claim:

1. Method of producing a masterbatch of reinforced rubber or rubber-likematerial which comprises mixing together with agitation an aqueousdispersion of carbon black particles and a rubber latex to cause thecarbon black to become dispersed throughout said rubber latex subjectingthe premixed polymer dispersion and carbon black to a controlledpressure which approaches but does not exceed the point of polymerdegradation and which is in a range of from 500 p.s.i. to 8000 p.s.i.causing carbon particles to further disperse, regulating the pressure inaccordance with the molecular weight of the polymer, the mean surfacearea of the carbon particles and the proportion of carbon black topolymer used, and releasing pressure through an orifice to generateintense cavitational field forces and to combine substantial quantitiesof the finely divided carbon black particles with the pressurizedpolymer to provide for rubber reinforcement comparable with rubberreinforcement normally obtained by conventional dry mixing of carbonblack and rubber polymer.

2. Method of producing a masterbatch of reinforced rubber or rubber-likematerial which comprises the mixing together with agitation an aqueousslurry of carbon black and an aqueous dispersion of a rubber polymer tocause the carbon black to become distributed throughout the liquidpolymer instantaneously pressurizing the mixed polymer and carbon blackby subjecting the mixture to a controlled pressure which approaches butdoes not exceed polymer degradation and which occurs in a range of from500 psi. to 8000 psi. and simultaneously conducting the pressurizedpolymer and carbon black through an orifice instantaneously releasingpressure to induce intense cavitational forces, and then coagulating theresulting fluid mass to produce a rubber crumb having significantlychanged solubility characteristics as compared with solubilitycharacteristics of a dry masterbatch.

3. A method according to claim 2 in which the step of coagulating thefluid mass consists in adding a creaming agent thereto with agitation.

4. Method of producing masterbatches of rubber or rubber-like materialwhich comprises the mixing together with agitation an aqueous slurry ofcarbon black and liquid latex body to cause the carbon black to becomedistributed throughout the liquid latex, instantaneously pressurizingthe mixed latex body and carbon black by subjecting the mixture topressures in a range offrorn 500 psi. to 8000 psi. and simultaneouslyconducting the pressurized latex and carbon black through an orifice,instantaneously releasing pressure to induce intense cavitationalforces, mixing the combined latex and carbon With a brine liquid,subjecting the mixture of brine, carbon and latex to a secondpressurizing step in a range of pressures of from 50 psi. up to 1000p.s.i. and then conducting the brine, latex and carbon black through anorifice and regulating the pressures exerted within the said 50 to 1000psi. range to control the degree of coagulation.

5. A method according to claim 2 in which the pressure and pH value ofthe finely divided material is controlled to provide coagulatingfractions of difiering chemical and physical properties.

References Cited UNITED STATES PATENTS 2,980,639 4/1961 Braendle 26041.52,986,547 5/1961 Jefts et al 26041.5 3,048,559 8/1962 Heller et a1.26041.5

ALLAN LIEBERMAN, Primary Examiner.

